1. Field of the Invention
This invention relates to a window blind, more particularly to an operating device for rotating a winding shaft of a window blind to wind up or winding down a curtain cloth.
2. Description of the Related Art
A conventional window blind generally includes a winding roller, a curtain cloth extending downwardly from the roller, and a ring chain (or cord) disposed on an end portion of the roller and extending downwardly. A user can pull the ring chain to rotate the winding roller such that the curtain cloth can be wound upwardly or downwardly. However, it is of no rare occurrence that the ring chain might wrap around a child's neck if the child sticks his/her head in the loop formed by the ring chain, thereby causing strangling incident. Another window blind such as those disclosed in EP Application No. 10157918.3 and U.S. patent application Ser. No. 12/696,173, is provided with an operating rod to replace the ring chain. The operating rod extends vertically and has an upper end coupled with a winding roller by a rotation transmitting mechanism such that vertical rotation of the operating rod results in horizontal rotation of the winding roller, and a lower end coupled with a hinged handle that is manipulated to rotate the operating rod. Since the hinged handle is disposed remote from the winding roller, a force applied to the handle is hard to be transmitted to the rotation transmitting mechanism, thereby rendering the operation laborious and inefficient.